This invention relates to the field of mounting devices and in particular to the mounting of equipment enclosures and the like on hollow, typically vertical, poles. In most prior art devices for mounting cabinet-type equipment on hollow poles, the devices had to be different for each pole size and different for each piece of equipment. Also, most such devices utilized mounting straps, rings or cables which made the equipment vulnerable to theft when mounted for access from the ground. Since easy access can be an essential requirement, as in the case of emergency communication equipment along a highway right-of-way, theft prevention becomes particularly important. Rigidity of mounting also is particularly important when the equipment location is exposed to high winds. Many prior art mounting devices for use on hollow poles required apertures of specialized shapes which are difficult to provide in poles already mounted by the roadside.